Messages in this thread | | | From | Geert Uytterhoeven <> | Date | Wed, 20 Jul 2022 19:31:01 +0200 | Subject | Re: [PATCH v2 6/9] Revert "driver core: Set default deferred_probe_timeout back to 0." |
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Hi Saravana,
On Wed, Jun 1, 2022 at 9:45 AM Saravana Kannan <saravanak@google.com> wrote: > This reverts commit 11f7e7ef553b6b93ac1aa74a3c2011b9cc8aeb61. > > Let's take another shot at getting deferred_probe_timeout=10 to work. > > Signed-off-by: Saravana Kannan <saravanak@google.com>
Thanks for your patch, which is now commit f516d01b9df2782b ("Revert "driver core: Set default deferred_probe_timeout back to 0."") in driver-core/driver-core-next.
Wolfram found an issue on a Renesas board where disabling the IOMMU driver (CONFIG_IPMMU_VMSA=n) causes the system to fail to boot, and bisected this to a merge of driver-core/driver-core-next. After some trials, I managed to reproduce the issue, and bisected it further to commit f516d01b9df2782b.
The affected config has: CONFIG_MODULES=y CONFIG_RCAR_DMAC=y CONFIG_IPMMU_VMSA=n
In arch/arm64/boot/dts/renesas/r8a77951-salvator-xs.dtb, e6e88000.serial links to a dmac, and the dmac links to an iommu, for which no driver is available.
Playing with deferred_probe_timeout values doesn't help.
However, the above options do not seem to be sufficient to trigger the issue, as I had other configs with those three options that do boot fine.
After bisecting configs, I found the culprit: CONFIG_IP_PNP. As Wolfram was using an initramfs, CONFIG_IP_PNP was not needed. If CONFIG_IP_PNP=n, booting fails. If CONFIG_IP_PNP=y, booting succeeds. In fact, just disabling late_initcall(ip_auto_config) makes it fail, too. Reducing ip_auto_config(), it turns out the call to wait_for_init_devices_probe() is what is needed to unblock booting.
So I guess wait_for_init_devices_probe() needs to be called (where?) if CONFIG_IP_PNP=n, too?
> --- a/drivers/base/dd.c > +++ b/drivers/base/dd.c > @@ -256,7 +256,12 @@ static int deferred_devs_show(struct seq_file *s, void *data) > } > DEFINE_SHOW_ATTRIBUTE(deferred_devs); > > +#ifdef CONFIG_MODULES > +int driver_deferred_probe_timeout = 10; > +#else > int driver_deferred_probe_timeout; > +#endif > + > EXPORT_SYMBOL_GPL(driver_deferred_probe_timeout); > > static int __init deferred_probe_timeout_setup(char *str)
Gr{oetje,eeting}s,
Geert
-- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds
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